Design and Simulation of ETL-Free Perovskite/Si Tandem Cell With 33%
Efficiency
AHMED SAEED1, MOHAMED MOUSA1, MOSTAFA M. SALAH1, A. ZEKRY2,
MOHAMED ABOUELATTA2, AHMED SHAKER2, FATHY Z. AMER3,
ROAA I. MUBARAK3
1Electrical Engineering Department, Future University in Egypt,
Cairo 11835,
EGYPT
2Electrical Engineering Department, Ain Shams University,
Cairo 11535,
EGYPT
3Faculty of Engineering, Helwan University,
Cairo 11795,
EGYPT
Abstract: - Multi-junction (tandem) cell using MAPbI3-xClx and silicon as absorbers has been designed and
simulated in this paper. The thickness of the silicon layer in the bottom cell is 2 μm allowing it to absorb the
transmitted spectrum from the perovskite subcell as much as possible. The thickness of the MAPbI3-xClx layer is
optimized using a proposed algorithm. The output metrics show that the optimum thickness of the MAPbI3-xClx
layer was 205 nm. The simulation outputs showed that the proposed tandem cell has an efficiency of 33.09% with
an open circuit voltage of 1.9 V and a short circuit current of 19.95 mA/cm2.
Key-Words: ETL free; High-efficiency; Perovskite; Si; Tandem.
Received: July 26, 2021. Revised: October 16, 2022. Accepted: November 17, 2022. Published: December 31 2022.
1 Introduction
Over the last few years, there has been a high energy
demand. According to statistics, fossil fuels have
been the primary source of energy consumed until
now. In the coming decades, it is estimated that
renewable energy sources, particularly solar cells,
will be the primary source of energy overtaking
fossil fuels,. The market for photovoltaics is
currently dominated by multi-crystalline and
monocrystalline solar cells made of crystallized
silicon. Single-junction solar cells made on
crystalline silicon now have power conversion
efficiencies of about 25%, [1], whereas the
perovskite photovoltaics have an average power
conversion efficiency of about 26%, [2], many
researches show a promising result of up to 30%, [3].
Single-junction solar cells are limited to absorbing
most of the incident AM1.5. One solution to this
limitation is using two or more subcells, each having
a different absorber layer with a different energy gap
and able to absorb different parts of the incident
light, [4], to build tandem cells.
The design and optimization of a two-subcell
multi-junction solar cell are presented in this paper
utilizing SCAPS-1D, [5]. The top (MAPbI3-x Clx)
subcell (PSC) consists of CuO, perovskite, and
transparent conductive oxide. This subcell is
designed without the electron transport layer (ETL)
as the transparent conductive oxide is highly doped
to apply the function of the electron transport layer
beside its primary role as a transparent layer, [6], [7],
[8], [9]. The bottom subcell consists of Cadmium
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
Ahmed Saeed, Mohamed Mousa,
Mostafa M. Salah, A. Zekry,
Mohamed Abouelatta, Ahmed Shaker,
Fathy Z. Amer, Roaa I. Mubarak
E-ISSN: 2415-1513
137
Volume 13, 2022
sulfide (CdS) and Zinc oxide (ZnO) layers with a
silicon (Si) absorber layer.
The ETL-free PSC is used as the top subcell rather
than conventional PSC as it exhibits improved
efficiency and stability. In addition, to improve the
output metrics of the multi-junction cell, the
influence of the thickness of the PSC top subcell
absorber layers is studied. The overall tandem cell is
assumed to be mechanically stacked and equivalent
to an ideal monolithic structure, [10], [11], [12].
The remainder of this work is structured as;
section 2 shows the structure, and simulation results
of the top ETL-free PSC, and introduces the bottom
silicon subcell; the algorithm used to obtain the
optimum thickness of the top subcell absorber layer
thickness to optimize the tandem cell efficiency is
given in section 3; section 4 concludes the work.
2 Formulation of Subcells
The designed ETL-free PSC structure is shown in
Figure 1 and specifically in Figure 1 (a). The
characteristics of the ETL-free PSC with the
thickness of the perovskite material are shown in
Figure 2. In this design, the transparent
conductive oxide (TCO) layer acts as its main
function and the ETL function. The simulation
materials are mentioned in Table 1, where
the simulation is performed using illumination
of AM1.5G at a temperature of 300 °K. The results
in Figure 2 shows that the short circuit current
density (JSC), Power Conversion Efficiency (PCE),
and Fill Factor (FF) of the designed tandem cell
increase with increasing the perovskite material
thickness up to about 800 nm and then
saturated. However, increasing the thickness of
the perovskite layer will lead to a decreasing the
open-circuit voltage (VOC). An essential note
that must be taken into consideration is that
the implantation of the practical thickness of the
absorber layer can not exceed 1000 nm. The
designed ETL-free perovskite solar cell shows
excellent performance with a high PCE of about
35%. Additionally, the design is simple.
The proposed Si bottom subcell design is
illustrated in Figure 1 and specifically Figure 1(b).
The J/V characteristics of this subcell are shown in
Figure 3. The simulation settings are the same as
in the previous simulations. The simulation shows
PCE = 16.35% with FF = 79.06 %, VOC = 0.496
V and JSC = 41.65 mA/cm2. The parameters used
in the simulation are given in Table 2.
(a)
(b)
Fig. 1: structure of (a) ETL-free Perovskite subcell;
(b) Silicon subcell.
Table 1. Parameters of ETL-free PSC subcell
Parameters
TCO
CuO
Energy gap (eV)
3.5
2.1,
[14]
Thickness (nm)
500
400
Relative permittivity
9
7.11,
[14]
Electron Affinity χ (eV)
4
3.2,
[14]
Effective
density of
states (cm -3)
NC
2.2×1018
NV
1.8×1018
mobility
(cm‒2 V‒1 s ‒1)
µe
20
3.4
µp
10
3.4
concentration
NA (cm -3)
0
1017
ND (cm -3)
2×1019
0
Density of defects Nt (cm -3)
1015,
[16]
1015
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
Ahmed Saeed, Mohamed Mousa,
Mostafa M. Salah, A. Zekry,
Mohamed Abouelatta, Ahmed Shaker,
Fathy Z. Amer, Roaa I. Mubarak
E-ISSN: 2415-1513
138
Volume 13, 2022
(a)
(b)
Fig. 2: ETL-free Perovskite subcell characteristics with
thickness: (a) VOC and JSC, (b) PCE and FF
0 0.1 0.2 0.3 0.4 0.5
0
10
20
30
40
50
Voltage(V)
J (mA/cm2)
PCE FF VOC JSC
16.35% 79.06% 0.496V 41.65 mA/cm2
Fig. 3: J/V curve of the Si bottom cell.
Table 2. Parameters of the Si subcell.
Parameters
ZnO
CdS
Si
Energy gap (eV)
3.30,
[18]
2.45,
[18]
1.12
Thickness (nm)
20
50
2000
Relative permittivity
9.0,
[19]
10.0
11.9
Electron Affinity χ
(eV)
4.6
4.4
4.05
Effective
density of
states (cm -3)
NC
2.2×1018
2.8×1019
NV
18×1018
26.5×1018
mobility
(cm‒2 V‒1 s ‒1)
µe
102
1450
µp
25
500
concentration
NA (cm -
3)
-
2×1016
ND (cm -
3)
1020
0
Density of defects Nt
(cm -3)
1014
3 Multi-Junction Cell
A numerical technique from [20] is used. A two-
phase algorithm is employed to optimize the
thickness: a course step of 50 nm and a small step of
5 nm. All the junction's performance characteristics
are computed based on the resultant thickness at each
stage. This algorithm is an improvement of the
algorithm from [21]. The modified algorithm is more
efficient than the one presented in [21] as the number
of overall computations decreases; the suggested
modification leads to a faster response for
determining the thickness of the top subcell absorber
for the 2-terminal multi-junction cell. Furthermore,
because the second phase's step size is decreased to 5
nm, it can determine the optimal thickness with
higher accuracy (the technique used in [21] has a
minimum step size of 10 nm).
ETL-free PSC/Si multi-junction solar cell has a
PCE of 33.09% when the perovskite thickness is 205
nm, as illustrated in Figure 4. The multi-junction cell
with AM1.5 and filtered AM1.5 are shown in Figure
5.
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
Ahmed Saeed, Mohamed Mousa,
Mostafa M. Salah, A. Zekry,
Mohamed Abouelatta, Ahmed Shaker,
Fathy Z. Amer, Roaa I. Mubarak
E-ISSN: 2415-1513
139
Volume 13, 2022
Fig. 5: Illumination of the ETL-Free Perovskite/Si
tandem solar cell.
The multi-junction overall cell with the highest
efficiency has a VOC of 1.9 V, JSC of 19.95 mA/cm2,
and FF of 87.29% as Figure 6 shows. The Quantum
Efficiencies (QEs) of the PSC and Si subcells and
the multi-junction cell are shown in Figure 7. At low
wavelengths, the QE of the multi-junction cell is
almost the same as the used ETL-free perovskite top
subcell, while it is about 100% up to the cutoff
wavelength (1107 nm) of the bottom subcell.
400 600 800 1000 1200
0
20
40
60
80
100
Wavelength (nm)
QE (%)
ETL Free
Perovskite
Si
ETL Free
Perovskite/Si
Fig. 7: Quantum Efficiencies of ETL-Free Perovskite
/Si subcells and tandem cell.
4 Conclusion
The designed tandem cell has a high-power
conversion efficiency and is presented with a
practical thickness range. A multi-junction solar cell
using perovskite and silicon as absorbers has been
presented. An optimization algorithm is presented to
optimize the thickness of the perovskite material.
The results show that electron transport-layer free
perovskite is a promising top sub-cell that can be
used with other bottom subcells rather than silicon,
the proposed tandem cell has an efficiency of
33.09%
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
Ahmed Saeed, Mohamed Mousa,
Mostafa M. Salah, A. Zekry,
Mohamed Abouelatta, Ahmed Shaker,
Fathy Z. Amer, Roaa I. Mubarak
E-ISSN: 2415-1513
140
Volume 13, 2022
Fig. 7: Quantum Efficiencies of ETL-Free
Perovskite /Si subcells and tandem cell.
References
[1] Yoshikawa, Kunta, et al. "Silicon
heterojunction solar cell with interdigitated
back contacts for a photoconversion efficiency
over 26%." Nature energy 2017, 2, 17032
[2] Yang, Woon Seok, et al. "Iodide management
in formamidinium-lead-halide–based
perovskite layers for efficient solar
cells." Science 2017, 356, 1376–1379.
[3] Salah, Mostafa M., et al. "A comprehensive
simulation study of hybrid halide perovskite
as oxide
Science and
solar cell with copper
HTM." Semiconductor
Technology 2019, 34, 115009.
Fig. 4: Tandem cell efficiency of ETL-Free PSC/Si
with various thicknesses of the top subcell absorber
material.
Fig. 6: ETL-Free Perovskite/Si subcells and
tandem cell J/V characteristics
[18] Wagner, Sigurd, et al. "CuInSe2/CdS
heterojunction photovoltaic detectors." Applied
Physics Letters, 25(8), 434-435.
[19] Salah, Mostafa M., et al. "Analysis of an
Efficient ZnO/GeTe Solar Cell Using SCAPS-
1D." Proceedings of Seventh International
Congress on Information and Communication
Technology. Springer, Singapore, 2023, pp.
677-685.
[20] Mousa, Mohamed, et al. "Simulation of
optimized high-current tandem solar-cells with
efficiency beyond 41%." IEEE Access, 9,
pp.49724-49737.
[21] Rabady, Rabi Ibrahim, and Hamza Manasreh.
"Thicknesses optimization of two-and three-
junction photovoltaic cells with matched
currents and matched lattice constants." Solar
Energy 158(2017):20-27.
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
E-ISSN: 2415-1513 141 Volume 13, 2022
[4]
[5]
[6]
Mousa, M., et al. “High efficiency tandem
perovskite/CIGS solar cell”. 2020 2nd
International Conference on Smart Power &
Internet Energy Systems (SPIES), Bangkok,
Thailand, 15–18 September 2020; pp. 224–
227.
Burgelman, M.; et al. “SCAPS Manual”;
University of Ghent: Ghent, Belgium, 2016.
Salah, Mostafa M., et al. "High-Efficiency
Electron Layer-Free Transport
Perovskite/GeTe Solar Cell: Tandem
Numerical Simulation." Crystals, 12(7), p.878.
[7]
[8]
[9]
Salem, Marwa S., et al. "Efficient perovskite
solar cell without electron transport
layer." International Journal of Electrical
Engineering and Technology, 34(12), p.1.
Salah, Mostafa M., et al. "Investigation of
Electron Transport Material-Free
Perovskite/CIGS Tandem Solar
Cell." Energies, 15(17), p.6326.
Basyoni, Marwa Sayed Salem, et al. "On the
Investigation of Interface Defects of Solar
Lead-Free
pp.130221-
Cells: Lead-Based vs
Perovskite." IEEE Access, 9,
130232.
[10]
[11]
[12]
Mousa, Mohamed, et al. "Simulation of High
open-circuit voltage Perovskite/CIGS-GeTe
tandem cell." 2022 IEEE 49th Photovoltaics
Specialists Conference (PVSC). IEEE, pp.
1230-1234).
Madan, Jaya, Rahul Pandey, and Rajnish
Sharma. "Device simulation of 17.3% efficient
lead-free all-perovskite tandem solar
cell." Solar energy 2020, 197, 212–221.
Mousa, Mohamed, et al. "Two-Terminal
Perovskite/Silicon Solar Cell: Simulation and
Analysis." 2021 3rd Novel Intelligent and
Leading Emerging Sciences Conference
(NILES). IEEE, pp. 409-412.
WSEAS TRANSACTIONS on ELECTRONICS
DOI: 10.37394/232017.2022.13.18
Ahmed Saeed, Mohamed Mousa,
Mostafa M. Salah, A. Zekry,
Mohamed Abouelatta, Ahmed Shaker,
Fathy Z. Amer, Roaa I. Mubarak
[13] Chae, Jungseok, et al. "Chloride incorporation
process in CH3NH3PbI3–x Cl x perovskites via
nanoscale bandgap maps." Nano letters 15, no.
12 (2015): 8114-8121
[14] Mehra, Rajesh. "Efficient design of perovskite
solar cell using mixed halide and copper
oxide." Chinese Physics B 27, no. 1 (2018):
018801
[15] Bansal, Shubhra, and Puruswottam Aryal.
"Evaluation of new materials for electron and
hole transport layers in perovskite-based solar
cells through SCAPS-1D simulations." 2016
IEEE 43rd Photovoltaic Specialists
Conference (PVSC). IEEE, pp. 1-4.
[16] Salah, Mostafa M., et al. "A comparative study
of different ETMs in perovskite solar cell with
inorganic copper iodide as HTM." Optik 178
(2019): 958-963
[17]Minemoto, Takashi, and Masashi Murata.
"Theoretical analysis on effect of band offsets
in perovskite solar cells." Solar Energy
Materials and Solar Cells 133 (2015): 8-14.
Conflicts of Interest
The author(s) declare no potential conflicts of
interest concerning the research, authorship, or
publication of this article.
Contribution of individual authors to
the creation of a scientific article
(ghostwriting policy)
The author(s) contributed in the present
research, at all stages from the formulation
of the problem to the final findings
and solution.
Sources of funding for research
presented in a scientific article or
scientific article itself
No funding was received for conducting this
study.
Creative Commons
Attribution License
4.0 (Attribution 4.0 Int
ernational, CC
BY 4.0))
This article is published under the terms of the
Creative Commons Attribution License 4.0
https://creativecommons.org/licenses/by/4.0/deed.en_US